glaucoides - kumlieni

(last update: January 26, 2012)

COMPARISON OF WINGTIP PATTERNS IN LARGE GULL.

We explain the scoring system in the section "primary classification"; a classification that was used by Howell and Mactavish to score adult Kumlien's Gulls in New Foundland (see: Identification and variation of winter adult Kumlien's Gulls, IN: Alula 1/2003). We hope to present similar scorings from Iceland, using the same standard classification to make easy comparisons. So far, images from Iceland, kindly provided by Hans Larsson from Sweden, show birds falling in "Stage 0" (unmarked white wingtip) to "Stage 3" (darker grey marks on the outer three to four primaries with subterminal marks on one to three primaries). As you can see (click thumbnails to view pages), there is variation within the stages, with darker patches ranging from very inconspicuous, ill-defined pigmentation to rather dark grey pigmentation. However, within each stage, patterns look similar and stages are merely defined on "number of primaries showing pigmentation" and "presence of (complete) sub-terminal bands".

Below: primary patterns as illustrated in Olssen.

- Gulls of North America, Europe, and Asia by Klaus Malling Olssen & Hans Larsson

17. Thayer’s Gull or Kumlien’s (Iceland) Gull
This example could represent minimal dark streaking in Thayer’s, with no dark markings on P5, or maximal dark streaking in Kumlien’s.

18. Kumlien’s (Iceland) Gull
There is large individual variation in this form, which is often regarded as a hybrid population between Thayer’s and Iceland L. g. glaucoides. Kumlien’s has dark grey, not blackish streaks in outer wing, with no dark markings on P5. Figure 18 shows maximum amount of dark.  

1-3. Kumlien’s (Iceland) Gull
Figures 1-2 show diagnostic frosty grey streaks of typical Kumlien’s, with dark not reaching inner webs, and upper wing paler than in Thayer’s.
Figure 3 shows minimal dark, but suggestion of patterning suggests Kumlien’s rather than Iceland.